Methods of shaping metals under high hydrostatic pressure



C. SAUVE June 24, 1969 METHODS OF SHAPING METALS UNDER HIGH HYDRGSTATIC PRESSURE Filed Oct. 19, 1966 FIG. 2

FIG. I

lNVEN'I OR CHARLES 5mm:

A'ITORNEY3 United States Patent 36,138 Int. Cl. B21d 22/10, 25/18; B21c 23/027 US. C]. 7260 Claims ABSTRACT OF THE DISCLOSURE The metal to be shaped by extrusion under high hydrostatic pressure is placed in the pressure chamber blocking the opening in the shaping die and is covered with a liquid lubricant. A second metal is placed in the receiving container blocking the opening of the extrusion die and is covered by a second liquid lubricant which fills the receiving container. High hydrostatic pressure created in the pressure chamber by force applied to the first liquid lubricant, upon inward movement of the sliding ram, extrudes the metal in the pressure chamber through the shaping die and into the receiving container. The pressure created in the second liquid lubricant by the penetration thereinto of the shaped metal body exiting from the shaping die is suflicient to extrude the second metal out of the receiving container through the extrusion die.

The United States application Ser. No. 388,501, filed Aug. 10, 1964, now Patent 3,286,337 related to improvements in methods of shaping metals under high hydrostatic pressure, especially metals which cannot readily be deformed under the usual conditions.

The improvements aforesaid consisted both in shaping under a substantially higher hydrostatic pressure than that which is necessary for producing deformation and in combining successive deformations which are well-defined and limited in amplitude but which are uniform throughout the mass of metal and which are effected over a predetermined temperature range and also in carrying out if necessary annealing operations performed within a given temperature range according to predetermined cycles and for pre-established lengths of time.

In the patent referred to, consideration was given mainly to the case in which said deformation process was carried out within a chamber in which a high pressure is maintained by artificial means such as a second metal which is transformed into a plastic state under the pressure applied by the first metal to be deformed and which is permitted to flow out only through an orifice of small caliber which can be made adjustable so as to obtain a predetermined hydrostatic pressure regime during the course of operations. In particular, it has been observed that the low real strength of the second metal referred to was multiplied by 2 n wherein S is the cross-sectional area of the metal in the plastic state and S is the cross-sectional area of the discharge orifice.

The primary object of this invention is to improve the methods described in the patent aforesaid, wherein said deformation is produced by means of an extrusion process as performed in particular on slugs for the purpose of obtaining rods or tubes having especially a circular crosssectional configuration. The improvements thus achieved make it possible in particular to ensure a better distribution of the hydrostatic pressure around the deformed material and prevent the extruded metal from being displaced with friction within a receiving container While providing a further advantage in that said second metal can be taken from stock of larger diameter which makes it possible to increase the extrusion ratio and therefore the pressure within said receiving container.

This invention mainly consists both in transmitting an extrusion pressure to the metal to be extruded by means of a first Newtonian liquid which is stable at the working temperature and in receiving said metal as it passes out of a first die within a receiving container filled With a second Newtonian liquid which is also stable at the working temperature and which can be identical with the first liquid, provision being made within the receiving container for a second metal which is rendered plastic under the pressure applied by the first metal as it penetrates into said receiving container whilst said second metal can be discharged from said container only through an orifice of small caliber which can be made adjustable and which can especially be a second die.

Aside from this main arrangement, the invention consists in a number of other arrangements which are preferably employed at the same time and which are to be considered either separately or in combination, viz:

said extrusion pressure is applied to said metal to be extruded by means of a ram slidably mounted in a pressure-resistant chamber which communicates with said receiving container by way of said first die;

said chamber and said receiving container are constructed as a single unit;

said chamber and said receiving container constitute two separate units which are continuously applied against each other under pressure on each side of said first die as a result of the action of hydraulic jacks, thus permitting of easy changing of said first die;

said first die has internal surfaces which are tapered on two sides;

said ram of said chamber has an extension in the form of a mandrel of smaller diameter which permits of extrusion of tubes;

said metal to be extruded is beryllium;

said second metal is selected from the following metals:

copper, aluminum, lead;

said Newtonian liquids are lubricants.

A better understanding of the invention will in any case be gained from the complementary description which follows below and from the accompanying drawings, said description and drawings being given primarily by way of indication and not in any limiting sense.

In the accompanying drawings:

FIG. 1 is an axial sectional view of a first device which permits the utilization of the method according to the invention for the extrusion of a rod;

FIG. 2 is an axial sectional view of a second device which permits the utilization of the method according to the invention for the extrusion of a tube.

From these figures, it is apparent that the extrusion chamber is constituted by a pressure-resistant cylinder 1 within which is slidably fitted a ram 3 for transmitting an extrusion pressure to the metal 5 to be extruded through the intermediary of a first liquid 7 or so-called Newtonian liquid, that is to say a liquid which does not have a shear coefiicient, which is stable at the working temperature and which can be a lubricant. In the case of FIG. 1, the liquid 7 is isolated from the ram 3 by means of an obturator 9 having the general shape of a disc. In the case of FIG. 2, the liquid is isolated from the ram by means of an obturator 11 having the general shape of a ring providing a central passageway for a mandrel 13 which forms as extension of the ram 3 in order to permit the extrusion of a tube.

The receiving container is constituted by a cylinder 15 affording resistance to the back-pressure which is applied to a second Newtonian liquid 17 having characteristics which are similar to those of the first liquid 7. Said second liquid can also be a lubricant and can in fact be identical with the first liquid 7. The back-pressure within the liquid 17 is established by virtue of the extrusion of a second metal 19 which is converted to the plastic state under the pressure which is developed as a result of the penetration into the liquid 17 either of the extruded rod 21 shown in FIG. 1 or of the extruded tube 23 shown in FIG. 2. The extrusion of the second metal 19 is carried out through a second die 25 which is placed at the bottom of the receiving container 15 and fixed in a base 27.

In a preferred embodiment of the invention which is shown in the figures, the chamber 1 and receiving chamber 15 constitute two distinct units separated by the first die 29 which may advantageously be internally tapered on two sides, these two units being joined together as a result of the pressure exerted on the first die 29, this holding pressure being transmitted by said first die between the two units which can thus have either equal or difierent diameters. These two units can be maintained under pressure by the action of hydraulic jacks.

By means of the arrangements which have just been described, the rod 21 or tube 23 is not displaced with friction within the receiving container 15 after discharge from the die 29 but, on the contrary, is displaced within the lubricating medium 17. It is further apparent that the metal 19 which has the function of establishing the backpressure is taken from large-diameter stock, thereby per-' mitting the possibility of increasing the extrusion ratio 8 /8 and therefore the value of said back-pressure.

The possibility of readily changing the die 29 which is permitted by the arrangements herein described constitutes a further substantial advantage for the purpose of utilizing the device on an industrial scale.

Finally, the improvements which have just been described can be applied to the extrusion of beryllium and the second metal 19 can be either copper, aluminum or lead, these metals being mentioned solely by way of nonlimitative example.

As has in any case become apparent from the foregoing, the present invention is not limited to the modes of application or to the examples of construction which have been more especially described herein and illustrated in the accompanying drawings but extends, on the contrary, to any or all variants which may be contemplated.

What I claim is:

1. In shaping a metal by extrusion under high hydrostatic pressure from a pressure chamber through a shaping die and into a liquid in a receiving container against pressure created by a second metal as it is being simultaneously extruded out of the receiving container through a second extrusion die, the process comprising the steps of placing a body of the metal to be shaped in the pressure chamber and blocking the opening in the shaping die; completely covering the body of metal in the pres sure chamber with a first Newtonian liquid which is stable at the working temperature; placing a body of a second metal in the receiving container and blocking the opening in the second extrusion die; completely filling the remainder of the receiving container and completely covering the second body of metal with a second Newtonian liquid which is stable at the working temperature; and applying a high hydrostatic pressure to the first N wtonian liquid sufiicient to extrude the metal in the pressure chamber through the shaping die and into the second Newtonian liquid in the receiving container and to simultaneously extrude the second metal in the receiving container through the second extrusion die and out of the receiving container by the pressure created in the second Newtonian liquid upon the penetration thereinto of the shaped metal body exiting from the shaping die.

2. A process according to claim 1, wherein said metal to be shaped is beryllium.

3. A process according to claim 1, wherein said second metal is selected from the group consisting of copper, aluminum and lead.

4. A process according to claim 1, wherein said first and second Newtonian liquids are lubricants.

5. Apparatus for shaping a metal by extrusion under high hydrostatic pressure, comprising: a receiving container; a pressure chamber; a shaping die disposed between and connecting the receiving container and the pressure chamber; an extrusion die mounted in the wall of said receiving container with the opening thereof connecting the interior of the receiving container to the exterior thereof; a body of metal disposed in the pressure chamber and blocking the opening of the shaping die; a first Newtonian liquid in the pressure chamber completely covering the body of metal; a ram slidably mounted in said pressure chamber in contact with the first Newtonian liquid for acting thereon and creating a high hydrostatic pressure; a body of a second metal disposed in the receiving container and blocking the opening of the extrusion die; and a second Newtonian liquid covering the second body of metal and completely filling the receiving container, whereby a high hydrostatic pressure created in the pressure chamber by the ram acting on the first Newtonian liquid results in the extrusion of the metal in the pressure chamber through the shaping die and into the second Newtonian liquid in the receiving container and simultaneously, due to the pressure created in the second Newtonian liquid by the penetration thereinto of the shaped metal body exiting from the shaping die, the second metal is extruded through the extrusion die and out of the receiving container.

6. Apparatus according the claim 5, wherein said chamber and said receiving container constitute two separate units which are connected together by the shaping die; said shaping die having an annular tapered wall portion on either side thereof, the pressure chamber and the receiving container having an opening in the wall thereof mating in sealing relation with said annular tapered wall portions, and said pressure chamber being continuously forced toward'the receiving container during extrusion operations to thereby seal the shaping die against the mandrel of smaller diameter than that of the opening of the shaping die, said mandrel moving axially through the opening in the shaping die as the ram slides into the pressure chamber during extrusion operations whereby the metal is shaped in the form of a tube.

References Cited UNITED STATES PATENTS 2,558,035 6/ 1951 Bridgman 72-54 3,344,636 10/1967 Pugh 72-60 3,354,685 11/1967 Green 72-253 3,364,717 1/1968 Green 72-253 RICHARD J. HERBST, Primary Examiner.

US. Cl. X.R. 72-261, 271 

